In general, the conventional doorbell is provided with three chiming tubes, as shown in FIG. 1, or four chiming tubes, as shown in FIG. 2. In other words, the conventional doorbell must be provided with two kinds of PC boards, depending on the number of the chiming tubes that the doorbell has. In addition, the conventional doorbell must be also provided with three or four hanging bases to facilitate the mounting of three or four chiming tubes. As illustrated in FIG. 3, the hanging bases are first fastened with the doorbell base before the striking device is secured to the receiving slot located under the hanging bases. Thereafter, the PC board is fastened with the hanging bases such that the bottom of the PC board is located securely in the recesses of the hanging bases, and that the top of the PC board is fastened with the doorbell base, and further that the PC board is connected with the coil of the striking device. In the case of the doorbell with three chiming tubes, each of three chiming tubes is provided with a chiming plate whose bottom end is received in the tube. The chiming tubes are fastened respectively with a locating piece which is in turn fastened onto the wall. The chiming plate is provided at the top end thereof with a through hole in which a plug is located such that the plug is retained in a U-shaped slot located in the back of the hanging base so as to facilitate the striking of the chiming plate by the striking bar of the striking device. In the case of the doorbell with four chiming tubes the chiming tubes are fastened with a locating board which is provided with a through hole for engaging a hanging plate of the hanging bases so, as to enable the striking bar to strike directly the chiming tubes.
Such a conventional doorbell base as described above is defective in design in that it is rather complicated in construction, and that it is not cost-effective. In addition, the PC boards of different sizes must be used for the doorbell with three chiming tubes and the doorbell with four chiming tubes.